Cell adhesion is a process by which cells associate with each other, migrate towards a specific target or localize within the extra-cellular matrix. As such, cell adhesion constitutes one of the fundamental mechanisms underlying numerous biological phenomena. For example, cell adhesion is responsible for the adhesion of hematopoietic cells to endothelial cells and the subsequent migration of those hematopoietic cells out of blood vessels and to the site of injury. Thus, cell adhesion plays a role in pathologies such as inflammation and immune reactions in mammals.
Integrins are a large family of cell surface receptors that mediate cell-cell and cell-matrix interaction. They exist as non-covalent αβ heterodimers of different combinations of α and β chains and share extensive structural homology. There are at least 18 different α subunits (α1α11, α-L, α-M, α-X, α-IIB, α-V and α-E) and at least 9 different β (β1–β9) subunits. Based on the composition of its α and β subunit components, each integrin molecule is categorized into a subfamily. Integrins mediate a wide variety of physiological processes and are relevant to a wide variety of pathological conditions. During inflammatory responses, α4β1 regulates leukocyte migration into the damaged tissues and thus has been recognized as an attractive therapeutic target. α4β1 integrin is also known as very late antigen-4 (“VLA-4”) or CD49d/CD29.